The Human Immunodeficiency Virus (HIV) is a retrovirus that destroys the immune system, causing the devastating disease known as the acquired immune deficiency syndrome (AIDS). In order to accomplish these effects, HIV subverts host defenses, altering normal functions to its own advantage. Dendritic cells (DCs) are antigen presenting cells that capture and process incoming pathogens, in order to present antigenic peptides to T lymphocytes and thereby elicit an immune response. Since DCs are among the first cells to encounter incoming HIV, the virus:cell interaction has been the focus of considerable research. Recent studies have found DCs are capable of capturing HIV and retaining the virus in an infectious state, then enhancing viral delivery to target cells in co-culture thereby increasing HIV infectivity. However, the mechanism involved in each of these processes remains unknown. This project will focus on identification of the endocytic pathway used by HIV to avoid degradation and characterization of the intracellular storage compartment within DCs. To achieve these goals, endocytic pathways will be suppressed through use of various chemicals and dominant negative constructs. The ability of DCs to pass infectious HIV to target cells in trans following each treatment will be determined through use of a luciferase reporter viral construct. High resolution fluorescent microscopy will be employed to examine the intracellular storage compartment in great detail. HIV will be visualized through use of a fluorescently tagged viral construct, and various markers of endocytic compartments will be used to characterize the storage compartment. The chemicals used to block endocytic pathways will also be examined for their ability to alter intracellular trafficking of HIV. Additionally, the effect of DC maturation on endocytosis and intracellular storage will be examined through the methods detailed above. Relevance: With over 40 million people currently living with HIV/AIDS worldwide, there is a constant need for development of better therapeutics and more efficient prevention strategies. As DCs are the first cells to encounter incoming HIV, targeting DCs directly may prove to be a successful approach to vaccine development. This proposal will answer important questions about the mechanism of HIV capture and storage by DCs, thereby contributing to the overall understanding of the HIV:DC interaction.